1. Field of the Invention
The present invention relates to an apparatus for depositing film with a uniform thickness and a method thereof. More particularly, the present invention relates to an apparatus for uniforming the thickness of a vapor deposition film and a method thereof.
2. Description of Related Art
Angle vapor deposition is one of vapor deposition methods, and the vapor deposition object is placed at a tilt angle with respect to the evaporation source. For example, U.S. Pat. No. 5,268,781 issued to JVC, U.S. Pat. No. 6,426,786 issued to IBM, and U.S. Pat. No. 6,771,341, etc. FIG. 1 is a schematic diagram illustrating a conventional angle vapor deposition. Atoms emitted from the evaporation source 10 are deposited on a substrate 20 placed over the evaporation source 10 to form a thin film thereon. The normal line N of the substrate 20 is tilted by an angle θ with respect to an atom emission direction of the evaporation source. Referring to FIG. 1, since the substrate 20 is disposed at a tilt angle θ, one side of the substrate is away from the evaporation source while another side thereof is closer to the evaporation source. Accordingly, differences in the deposited film thickness will occur due to different deposition positions on the substrate 20 within a specified period. To resolve the foregoing non-uniformity issue of the film thickness, methods are provided that atoms emitted from the evaporation source can be evenly deposited on the substrate by using the revolution or rotation of the vapor deposition objected.
The angle vapor deposition process may also be applied to the fabrication of liquid crystal display panels, whose structure intrinsically has an alignment film. Since the alignment film has to be aligned at the same direction, the vapor deposition object cannot be rotated while evaporating alignment film. Rotating the vapor deposition object may result in the aforementioned adverse effect for the uniformity of film thickness. The thickness variation of the alignment film may cause instability in the optical and electrical characteristics of products. Thus, it is very difficult to fabricate a thin film having a large area and a uniform thickness by using the angle vapor deposition process.
Moreover, different material used as the target in the vapor deposition has different emission characteristics, and different emission characteristics may cause different distribution of film thickness. Therefore, it is a great challenge for controlling the thickness uniformity of each film.